
/**
 * @Project : Clion_ProgrammingExercises
 * @File : 0790
 * @Author : WangRuoyu 
 * @Date : 2023/5/20 11:29
 */

#include "iostream"

using namespace std;

int main() {
    double x;
    scanf("%lf", &x);

    double l = -1e5;
    double r = 1e5;

    while (r - l > 1e-8) {
        double mid = (l + r) / 2;
        if (mid * mid * mid > x) r = mid;
        else l = mid;
    }

    printf("%.6lf", l);

    return 0;
}